Currently, polyarylene sulfide is representative engineering plastic, and is in great demand for high temperature and corrosive environment and electronic products due to high heat resistance, chemical resistance, flame resistance, and electric insulation. The major uses include computer accessories, automobile accessories, coating of the part contacting corrosive chemical materials, and industrial chemical resistant fiber, and the like.
Presently, polyphenylene sulfide (PPS) is the only commercially available polyarylene sulfide. According to the current commercial production process of PPS, p-dichlorobenzene (pDCB) and sodium sulfide are used as raw materials and reacted in a polar organic solvent such as N-methyl pyrrolidone, and the like. This method is known as a Macallum process, and the basic process is disclosed in U.S. Pat. Nos. 2,513,188 and 2,583,941, wherein some usable polar solvents are suggested, but N-methylpyrrolidone is currently most commonly used. This process uses dichloro aromatic compounds as raw material, and sodium chloride (NaCl) is generated as a by-product.
The polyphenylene sulfide obtained in the Macallum process includes residues such as sodium sulfide and organic solvent such as N-methylpyrrolidone, and the like to some degree. Due to the existence of the residues, decomposition may occur during use of the polyphenylene sulfide, and particularly, if it is melt-processed for recycling, decomposition of polyphenylene sulfide by resides may occur more significantly.
Accordingly, deterioration of mechanical properties according to use of polyphenylene sulfide after polymerization is often observed, and if it is molten and molded for recycling of the resin, mechanical properties may be further deteriorated, and thus, there is significant limitations in recycling of expensive polyphenylene sulfide.